So water is leaking from somewhere inside my furnace. I turned the A.C. off and a fair amount of water came out of the drain on the outside of the house. Before all of this happened I had extended the drain outside by adding a 6 foot section of PVC to the copper pipe coming out of the house.The copper pipe was less than a foot long. Any chance adding the PVC causes a problem?

 

No.. But remove the coil cover and check.. sounds like the coil may be clogged causing high static pressure..

 

Not sure where that is located. One suggestion I've seen is to attach a wet vac to the drain outside and suck out whatever might be clogging it up.

 

Welcome to the forums.

Look at the side of the furnace where the refrigerant lines connect. You should see two 3/4" fittings..... usually PCV.... where the drains connect. One is slightly lower than the other one. That is the primary drain. The higher one is the overflow or backup drain and may be capped off. Depending on how your furnace is set up.... it may be creating a vacuum on the drain line causing it to overflow inside. That piece you added to the drain could be the reason. You may need to put a trap in the drain line to ensure a reliable drain.

You can post a picture or two and we can comment further...... How-to-insert-pictures.

 

The second picture (upside down sorry)is where the refrigerant is attached to the furnace ...i think the larger pipe wrapped in black insulation ? Just below it is the copper drain pipe that runs outside of the house. The first picture shows what you were describing...I think...there's the PVC pipe coming out and on the other side ..not visible in the picture is another exit for a second PVC pipe that was capped and sealed with silicone. The pvc pipe in the picture wraps around the furnace and is attached to the humidifier.